1. Filed of The Invention
The present invention relates to an oil field choke valve apparatus with an improved safety locking arrangement that prevents removal of the main wing nut from the choke without first removal of a bleeder plug so that the operator will be warned if the system is still under pressure when the bleeder plug is backed off of its seat. Even more particularly, the present invention relates to a safety interlock system for an oil field choke valve apparatus which features an improved clamping arrangement that loads the connection of a bleeder plug body, an interlock clamp plate, the wing nut, and the choke valve body to deliver several hundred pounds of force, securing the bleeder plug body and clamp plate firmly into position on the choke valve body.
2. General Background
Oil field choke valves have been used commercially for a number of years. Many choke valves are the subject of issued patents. For example, the Baker U.S. Pat. No. 3,426,797 entitled "Multiple Orifice Valve" relates to a fluid control valve having an axially aligned inlet and outlet with relatively rotatable flow controlling disks in face engagement containing respectively a pair of similarly positioned diametrically opposed orifices, a cylindrical disk carrier fixedly mounting one of the disks having a central passage containing a separate sleeve liner connecting the disk orifices with the outlet. A rotatable cylindrical disk carrier mounts the other disk and has an actuator handle extending outward through the arcuate slot in the valve body. This carrier is sealed on opposite sides of the slot, the body being grooved between the seals and provided with a drain port. The rotatable carrier provides a central passage connecting its disk orifices with the inlet and being connected through a port passage with an annular chamber extending about the interface of the disks. The '797 patent was assigned to Willis Oil Tool Co. of Long Beach, CA. Willis, division of Smith International, Inc. sells a number of multiple orifice valves in various sizes. The Smith International, Inc. valves which are sold under the Willis name include for example Model M2 and Model M2G multi-orifice valve chokes.
U.S. Pat. No. 3,331,396 issued to R. S. Willis and entitled "Orifice Valve" discloses a multiple orifice valve usable in the control of flow of abrasive fluids such as the fluids produced from oil wells and the like. Such orifice valves of the '396 patent for example are used in the control of for example well production fluids, to control the rate of flow through a flow line within a range predetermined by the number and size of a plurality of orifices in a relatively stationary orifice disk or member and a rotatable disk or member. The orifices are adapted to be brought more or less into alignment upon angular movement of the rotatable orifice disk.
There are commercially available chokes which allow pressure relief through a bleeder assembly prior to the opening of the valve by removal of a wing nut. However, these valves suffer because many times the valve design does not provide a strong interface between a bleeder assembly and the valve body. This prevents a potential problem of leakage, and possibly valve failure if the bleeder plug assembly (plug body and plug) become loosened in connection with the entire apparatus of the choke.
U.S. Pat. Nos. 3,426,797 and 3,331,396 are hereby incorporated herein by reference.